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Wireless Basics

Introduction

At SmallNetBuilder, we're big on having shoppers understand their requirements so that they can buy a product that best suits their needs. But not everyone, especially folks whose first interest is not home networking, wants to know the intimate details of how wireless routers work.

So if you don't want (or care) to get into the details behind what makes a wireless router tick and just want the essential information you'll need to avoid taking home the wrong router, then this article is for you.

Router Types

The types of routers you can buy seems to have exploded over the three years since the last version of this article. But, in reality, there is really only one new option, making three basic types.

G

N

Draft AC

These type abbreviations come from the IEEE 802.11n standard they are based on, i.e. 802.11g, 802.11n anddraft 802.11ac. Yes, that's right, at this point in time, we have another round of products on the market based on yet another unreleased standard. Unlike 802.11n, this time manufacturers are shying away from advertising the fact that AC products are based on a standard that isn't released.

Their explanation is that draft 11n products confused buyers and they don't want to do that with 11ac. (Isn't that nice of them?) 802.11ac is currently scheduled to be released in November 2013 according to the official IEEE timeline.

Dual-band, by the way, means products that operate in both the 2.4 and 5 GHz Wi-Fi frequency bands. You can tell if a product is dual-band if it lists 802.11abg or abgn in its specs.

The main variations within each router type are:

Port Speed - WAN and LAN ports are Gigabit Ethernet (10/100/1000 Mbps) or 10/100 Mbps. Gigabit LAN ports are good to have, if you have devices with Gigabit Ethernet ports.

But you can always buy a router with 10/100 ports and pick up a 5 port Gigabit Ethernet switch later (~ $35) if you upgrade your wired network. And you have no need for a Gigabit WAN port unless your internet connection is > 100 Mbps.

USB Ports - USB 2.0 and USB 3.0 ports can share storage and /or printers.
Don't get your hopes up on printer sharing. If it works at all, you'll find that anything other than printing on a multifunction printer won't work. And things like ink status and paper out messages probably won't make their way back to your computer.

Compatibility is better for storage sharing. But speeds are generally not equal to those on dedicated NAS (Network Attached Storage) products. And you may find that built-in media servers don't work with your players or are lacking in features you want.

Legacy Products

There are two older product types—A and B—that aren't in the list above that are considered "legacy" products.

802.11a defined the original 5 GHz-only Wi-Fi products and 802.11b defined original 2.4 GHz Wi-Fi gear. 5 GHz only routers never caught on and today you find references to 802.11a only in dual-band products. B only routers were long ago replaced by G routers, which have since just about been replaced by N types.

G routers are still required to support B devices and N routers are required to support both B and G devices in order to be Wi-Fi Certified. And AC routers will be required to support B, G and N devices going forward. But because your shiny new router can support these older, slower device types doesn't mean that they should.

In heavy use, B and G devices can eat up bandwidth and slow down your faster N devices. You may also need to change the mode settings on your router to get certain "legacy" devices to work. So you may be better off keeping your old router and adding a new one. See Add, Don't Replace When Upgrading to 802.11n for more details.

Router Sub-Types

The greatest variation you'll find for now is within the N routers. Once AC routers get going, you can expect telling them apart to be even more confusing then N's.

Within N routers, you'll find six sub-types. These can often be identified by a telltale number somewhere in their product name or marketing material. This number denotes the maximum link rate that the product supports.

You will often see SNB reviews refer to the number of "streams" a router supports. Streams are part of the MIMO (Multiple Input Multiple Output) technology that makes 802.11n and ac work. All you need to know is that single-stream N devices support a 150 Mbps maximum link rate, dual-stream devices support 300 Mbps and three-stream N devices' link rates max out at 450 Mbps.

This number is supposed to trick you into thinking that it's the actual speed that your wireless devices will run at. But it's really an indication of the technology used in the product and only good as a relative speed indicator.

Actual real-life throughput will be at best 50% of the "N number" you see in marketing material and more typically closer to 20 - 25%. This means an "N300 router" will deliver more like 60 Mbps of actual best case throughput.

Table 1 lists the numbers you are likely to see during your wireless router hunt and what they mean.

"N" number

Found in

Best case client "speed"*

150

2.4 GHz cheap routers, travel routers, "mobile companions"

65 / 150

300

2.4 GHz mainstream N routers

130 / 300

450

2.4 GHz "premium" routers or as second radio (either 2.4 or 5 GHz) in "N750" routers

217 / 450

600

Mainstream simultaneous dual-band N routers

130 / 300

750

"Premium" simultaneous dual-band N routers

130 / 300
217 / 450

900

Top-of-line simultaneous dual-band N routers

217 / 450

1750

Draft AC routers

217 / 450
217 / 450 / 1300

Table 1: N product types

The first thing you need to know is that all the numbers above 450 are sums of the maximum link rates of each radio. So each radio in an "N600" router maxes out at 300 Mbps and at 450 Mbps in an "N900" router.

The next thing you need to know is that the N number is 2X the number you are likely to see reported by Windows Wireless Network Connection Status when you first connect to your new N router. This is because N routers support two sets of maximum link rates depending on the bandwidth mode they are operating in.

The first number in the Best case client speed column in Table 1 is the best case when the router is in 20 MHz bandwidth mode and the latter is what you can see when the router is in 40 MHz bandwidth mode. I'll explain this more in a bit.

The most confusing N type is 750 because each band in the router has a different top link rate and there is no way of knowing which band it is, unless you dig into the product's data sheet. And, sadly, even then, it's near impossible to tell for some products. Some products support the maximum 450 Mbps link rate on the 2.4 GHz radio, while others support it on 5 GHz.

To confuse things even further, the rates you may see reported on your Windows notebook might be lower, depending on the chipset your client device uses. Some N adapters will show only maximum link rates of 117 / 270 instead of 130 / 300 and some N150 products may only show a maximum 135 Mbps link rate. This is due to the variations allowed by the 802.11n specification and it's all perfectly valid. A full list of 802.11 rates is here so you can have fun trying to find the "speed" number your computer is showing.

I expect Table 2 to expand in the next version of this article. But for now, it shows only one type of draft AC router because that is all that is being sold as I write this. See Why 802.11ac Will Kill The 5 GHz Wi-Fi Band if you want to know more about what's in store for AC routers.

"AC" number

Found in

Best case client "speed"*

1750

Draft AC routers

217 / 450 (2.4 GHz)
217 / 450 / 1300
(5 GHz)

Table 2: AC product types

Like N750 routers, the current crop of draft AC routers have two radios, each of which has a different maximum link rate. The 2.4 GHz radio has a 450 Mbps maximum link rate and the 5 GHz radio—which is the only one that supports draft 802.11ac—maxes out at 1300 Mbps, for a total of 1750 Mbps.

The last thing you need to know about these link rates is that both the router and device need to support them. If you have an N150 client connected to an N900 router, the highest link rate you're going to see reported by the device is 150 Mbps, no matter what settings you futz with on the router.

The rule is: The lowest link rate always wins. But just because one device operates at a less-than-maximum link rate, that doesn't mean all devices do. Routers are perfectly happy supporting each device at all the link rates it is capable of.